Hydrothermal synthesis of two new zinc coordination polymers with mixed ligands

The hydrothermal reactions of zinc acetate with 1,2,4,5-benzenetetracarboxylic anhydride (btc) and 4,4′-bipyridine (4,4′-bpy) for [Zn2(4,4′-bpy)(btc)(H2O)2]n·2nH2O (1) or imidazole (imi) for [Zn2(imi)4(btc)(H2O)2]n (2) in the molar ratio of 1:1:1:2000 at 170 °C for five days led to the formation of colorless crystals of 1 and 2. The btc ligand acts as a four-dentate bridging ligand in both compounds to link up zinc atoms into linear chain architectures. In 1, the linear chain subpolymers are further interlinked into a lamellar framework via 4,4′-bpy ligands. Finally, both 1 and 2 are extended into three-dimensional framework via hydrogen bonding.